Del Piero, who recently made the move to Sydney FC following reported interest from Liverpool, met up with the 65-year-old and described himself as a big "fan" of the musician.
"My little boy is 22 months old and loves soccer," The Sun quotes Elton as saying. "He's already kicking the ball around. He will love this."
The famous singer is a lifelong supporter of Watford and used to be the chairman of the club until 1987.